Dynamic control of gears in gear pumps with drive-drive configuration

Abstract

An apparatus includes a torque adjustment circuit for receiving a torque setpoint and a torque feedback signal corresponding to a differential torque between a pair of meshing gear teeth of a first gear and a second gear. The torque adjustment circuit is further configured to output a torque adjustment signal corresponding to the difference between the torque setpoint and the torque feedback signal. The apparatus also includes a motion control circuit for providing a first speed demand signal to a first motor driving the first gear and a second speed demand signal to a second motor driving the second gear, and for dynamically synchronizing the torque between the pair of meshing gear teeth by adjusting at least one of the first speed demand signal or the second speed demand signal, such that the differential torque between the pair of meshing gear teeth is within a predetermined range.

Description

[0001] priority

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 049307, filed July 8, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of this disclosure generally relate to a system and method for controlling a fluid pump, and more particularly, to a system and method for dynamically controlling the torque and / or position of gears in a gear pump having a drive-drive configuration. Background Technology

[0004] Gear pumps are commonly used in industrial fluid pumping systems, such as hydraulic systems in industrial equipment, aerospace, and other applications. In such systems, gear pumps are typically drive-driven systems, where one gear is coupled to a motor (drive gear), and the drive gear meshes with and drives another gear (driven gear) to transfer fluid from the pump inlet to the pump outlet. The tolerances between the gears must account for variations in parameters such as the operating temperature and pressure of the working fluid, ensuring that the teeth do not lock up as these parameters change. For example, as the fluid temperature rises from the starting conditions to the full operating temperature, the gears will increase in size, and the tolerances between the gears must ensure that there is always some "play" or "backlash" between them to prevent lockup. Additionally, the tolerances between the gears must allow the driven gear to "self-adjust" within limits based on the forces it experiences. For example, as the flow rate and / or discharge pressure change, the forces on the gear-to-gear contact also change. Because the driven gear in a drive-driven system is driven by another gear rather than by a motor at a precise angular velocity, the driven gear will automatically adjust to any changes in the forces between the gear teeth, if there are any tolerances between the gears.

[0005] Compared to a drive-driven gear pump, the applicant's U.S. Patent No. 10,072,676 ("'676 Patent") discloses the control of a pump with two fluid actuators (drive-drive pump). The '676 Patent discloses a drive-drive pump in which two gears are driven separately by their respective motors at precise angular velocities, and gear-to-gear contact is maintained by driving one gear "slightly faster" than the other. Clearly, the two gears will rotate at the same angular velocity (for a pump with a 1:1 gear ratio). This is because the teeth on the slightly faster-driven gear will contact the teeth on the other gear, and both gears will rotate at the same angular velocity. In operation, the difference in speed requirements of the two motors is set such that the contact force between the opposing gear teeth is expected to be high enough to maintain a seal between the opposing gear surfaces during all operating conditions.

[0006] In a drive-drive system where the contact force maintains a seal throughout all operating conditions, the two gears "self-adjust" based on changes in the force on the gears, not due to the flow rate, pressure, and temperature of the hydraulic fluid. For example, as the temperature rises, the gear teeth become larger, and the force on the gears increases. Therefore, in such a drive-drive system, the motor, gear teeth, and tolerances between the gears must be designed for worst-case stresses (which typically occur at the flow rate, pressure, and / or temperature experienced at the highest rated speed). However, if the drive-drive system is configured to operate under various operating conditions, designing for the worst-case scenario may mean that the drive-drive pump may be inefficient and / or not have the most economical configuration under normal operating conditions. Alternatively, if the drive-drive system is configured such that the appropriate contact force is applied under normal operating conditions, the contact force may be insufficient to maintain proper operation and / or efficiency during the worst-case scenario.

[0007] Furthermore, due to the manufacturing process, there is always some variation in gear tooth dimensions. This variation leads to variations in the contact force between corresponding meshing teeth. For example, within each rotation of the gear, the contact force between corresponding gear teeth can vary from almost no contact force (e.g., corresponding to torque less than 1 Nm, depending on gear configuration and / or gear size) to excessive contact force (e.g., corresponding to torque greater than 10 Nm, depending on gear configuration and / or gear size). Variations in the contact force between meshing teeth can lead to uneven and / or excessive wear and / or premature failure of gear teeth. To minimize the variation in contact force in critical and / or high-rpm pumps (e.g., greater than 6000 rpm), gears are manufactured with tight tolerances, which increases the cost of the system.

[0008] Other limitations and disadvantages of these methods will become apparent to those skilled in the art by comparing conventional, traditional proposed methods with the embodiments of the present invention as illustrated in the remainder of this disclosure with reference to the accompanying drawings. Summary of the Invention

[0009] Preferred embodiments of this disclosure pertain to a control system that can dynamically synchronize the torque and / or position between one or more pairs of meshing gear teeth of a gear pump based on operating modes from feedback from a fluid system and / or a control system. As used herein, "meshing gear pair" means a tooth on one gear and a corresponding tooth on another gear, which contact and / or form a small gap between them as the gears rotate and mesh. Depending on the gear ratio, the gear teeth may have one or more corresponding teeth on another gear. As used herein, "synchronized position" means controlling the position of one or more gear teeth relative to their corresponding teeth as the meshing gear pair rotates. As used herein, "synchronized torque" means controlling the differential torque between the motors to a predetermined value and / or within a predetermined range as one or more pairs of meshing gear teeth contact during rotation. As used herein, "differential torque" means the torque difference between the motor and / or gears.

[0010] In an exemplary embodiment, a pump control circuit can dynamically synchronize the torque and / or position between one or more meshing gear teeth of several pairs. The pump control circuit can be configured to adjust a first motor demand signal to a first motor driving a first gear and / or a second motor demand signal to a second motor driving a second gear based on feedback signals corresponding to the torque (e.g., differential torque) and / or relative position between one or more meshing gear teeth of the several pairs. In some embodiments, the motor demand signal is based on motor speed. However, in other embodiments, the demand signal may be based on motor current, motor drive frequency, motor voltage, motor power, and / or some other motor parameter. The pump control circuit preferably includes feedback circuitry configured to receive the feedback signal. Preferably, the feedback signal corresponds to system parameters (e.g., fluid density, viscosity, temperature, pressure, volumetric flow rate, and / or another property of the pumped fluid), pump parameters (e.g., pump rpm, pump temperature, and / or another pump parameter), motor parameters (e.g., motor current, motor voltage, motor power, motor frequency, and / or another motor parameter), gear parameters (e.g., gear rpm, gear tooth speed, gear tooth position, encoder feedback, and / or another gear parameter), and / or another feedback signal. In some embodiments, the feedback signal is related to the differential torque between the first gear and the second gear. In some embodiments, the feedback signal is related to the position of the first gear, the position of the second gear, and / or the relative position of the first gear and the second gear. Of course, as discussed above, other feedback can be used by the pump control circuit, along with appropriate circuitry, to dynamically synchronize torque and / or dynamically synchronize position.

[0011] In another exemplary embodiment, a pump system includes a pump assembly, preferably having a pump housing defining an internal volume. The pump assembly may include a first gear and a second gear arranged such that the first gear meshes with the second gear. The pump assembly includes a first motor for driving the first gear and a second motor for driving the second gear. Preferably, the pump system includes pump control circuitry configured to provide a first speed demand signal to the first motor and a second speed demand signal to the second motor. Preferably, the pump control circuitry is configured to dynamically synchronize torque based on a torque feedback signal and / or dynamically synchronize position based on a relative position feedback signal by adjusting the first speed demand signal and / or the second speed demand signal.

[0012] In another exemplary embodiment, a method for controlling a pump motor in a drive-drive configuration includes providing a first motor demand signal to a first motor driving a first gear and providing a second motor demand signal to a second motor driving a second gear. The method also includes dynamically synchronizing torque based on a torque feedback signal and / or dynamically synchronizing position based on a relative position feedback signal by adjusting the first demand signal and / or the second demand signal.

[0013] The "Summary" of this invention is provided as a general description of some embodiments of the invention and is not intended to limit any particular fluid-driven actuator assembly or controller system configuration. It should be understood that the various features and feature configurations described in the "Summary" can be combined in any suitable manner to form any number of embodiments of the invention. Additional exemplary embodiments, including variations and alternative configurations, are provided herein. Attached Figure Description

[0014] The accompanying drawings, which are incorporated herein and constitute a part of this specification, illustrate exemplary embodiments of the invention and, together with the general description given above and the detailed description given below, serve to explain the features of the exemplary embodiments of the invention.

[0015] Figure 1 This is a block diagram of a fluid-driven actuator system having a preferred embodiment of a fluid-driven actuator assembly and a control system.

[0016] Figure 2 An exploded view of an exemplary embodiment of a pump assembly having an external gear pump and a storage device is shown.

[0017] Figure 3 A cross-sectional view of another exemplary embodiment of a pump assembly having a drive-drive configuration and a motor mounted on the outside of the pump and located inside the pump is shown.

[0018] Figure 4 Show Figure 1 Top view cross-section of an external gear pump and illustrative flow path.

[0019] Figure 5 This is a schematic block diagram of a pump control system according to an embodiment of the present disclosure.

[0020] Figure 6A An illustrative graph showing the speed requirement of an external gear pump for the meshing gear pair is presented.

[0021] Figure 6B It shows the corresponding Figure 6A The curve of the meshing gear pair.

[0022] Figure 7 This is an enlarged view of the meshing region of an external gear pump using a clearance control scheme. Detailed Implementation

[0023] The exemplary embodiments of this disclosure pertain to a drive-drive control system in which the pump gears are driven in an operating mode that includes synchronous torque mode operation and / or synchronous position mode operation. The exemplary embodiments of this disclosure may also pertain to a gear pump comprising two gears for transferring fluid, wherein each gear is driven by its own motor. For example, the pump may be an external gear pump or an internal gear pump with a drive-drive configuration.

[0024] Preferably, the control system can dynamically synchronize the torque and / or position between one or more pairs of meshing gear teeth during operation of the gear pump. In some embodiments, the control system controls the gear pump based on feedback such as: system parameters (e.g., fluid density, viscosity, temperature, pressure, volumetric flow rate, and / or another property of the pumped fluid), pump parameters (e.g., pump rpm, pump temperature, and / or another pump parameter), motor parameters (e.g., motor current, motor voltage, motor power, motor frequency, and / or another motor parameter), gear parameters (e.g., gear rpm, gear tooth speed, gear tooth position, encoder feedback, and / or another gear parameter), and / or another feedback signal. In some embodiments, the pump control system can dynamically synchronize the torque between one or more pairs of meshing gear teeth to maintain the torque between corresponding gear teeth at a predetermined setpoint. For example, the pump control system can be configured to maintain differential torque between meshing gear teeth attributable to, for example, contact forces between teeth and / or system conditions (e.g., system pressure, flow rate, temperature, etc.). Preferably, the differential torque is maintained at a torque setpoint based on system conditions and / or pump operating conditions. In some embodiments, the torque feedback signal is based on a motor current feedback signal from one or both of the motors. In some embodiments, the pump control system may dynamically synchronize the positions of one or more pairs of meshing gear teeth so that the relative position between corresponding teeth (also referred to herein as “clearance width”) is maintained at a predetermined setpoint (e.g., a clearance width setpoint). Preferably, the predetermined setpoint may be based on pump operating conditions, such as, for example, the temperature of the fluid being pumped.

[0025] Figure 1 An exemplary block diagram of a fluid operating system 100 is shown. The fluid operating system 100 includes a fluid-driven actuator assembly 1 that operates a load 300. The fluid-driven actuator assembly 1 includes a fluid-driven actuator 3 (which may be, for example, a hydraulic cylinder, a hydraulic motor, or another type of fluid-driven actuator that performs work on an external load) and a pump assembly 2. When the fluid-driven actuator is a linear actuator such as a hydraulic cylinder, the load 300 can move in a linear direction, such as, for example, a linear direction 301. If the fluid-driven actuator is a rotary actuator such as a hydraulic motor, the load 300 can rotate, for example, in a rotational direction 302. The pump assembly 2 may include a pump 10, proportional control valve assemblies 222 and 242, and / or a storage device 170. The hydraulic actuator 3 can be operated by fluid from the pump 10, which can be controlled by an actuator control system 200.

[0026] Preferably, the actuator control system 200 includes a drive unit 295 having a pump control circuit 210 for controlling the pump 10 and / or a valve control circuit 220 for controlling the proportional control valve assemblies 222 and 242. The actuator control system 200 preferably includes a supervisory control unit 266 for the overall operation of the control system. The supervisory control unit 266 may include an operator input unit 276 for receiving commands from a user. The operator input unit 276 may be, for example, a human-machine interface (e.g., a keyboard, monitor, mouse, joystick, and / or another user interface). In some embodiments, the supervisory control unit 266 (and / or another controller) may include a load control circuit 267, which may include control logic (e.g., hardware, software, algorithms, etc.) for controlling the load 300. In some embodiments, the load control circuit 267 communicates with the pump control circuit 210 to operate the load 300. Preferably, the supervisory control unit 266 (and / or another controller) may include actuator control circuitry 268, which may include control logic (e.g., hardware, software, algorithms, etc.) for controlling the fluid-driven actuator assembly 1. In some embodiments, actuator control circuitry 268 communicates with pump control circuitry 210 to operate fluid-driven actuator assembly 1. The drive unit 295, having pump control circuitry 210 and / or valve control circuitry 220, may include hardware and / or software that interprets parameter feedback signals (e.g., signals related to system pressure, flow rate, temperature, valve, actuator and / or gear position and / or speed, motor current and / or voltage and / or some other measurement parameters) and / or command signals (e.g., flow rate and / or pressure setpoints and / or some other control signals) from the supervisory control unit 266 and / or the user via input unit 276, and sends appropriate demand signals (e.g., speed, torque and / or position demand signals and / or some other demand signals) to pump 10 and control valve assemblies 222, 242 to position load 300. For simplicity, the description of the exemplary embodiment is given with respect to a hydraulic fluid system having a hydraulic pump and hydraulic actuators (e.g., hydraulic cylinders, hydraulic motors and / or another type of hydraulic actuator). However, the inventive features of this disclosure are applicable to fluid systems other than hydraulic systems.

[0027] In some exemplary embodiments, the pump assembly 2 may include a storage device 170 for storing and releasing hydraulic fluid as needed. The storage device 170 may also store and release hydraulic fluid when the fluid density and therefore fluid volume change due to, for example, a change in fluid temperature (or a change in fluid volume due to some other reason). Furthermore, the storage device 170 may also be used to absorb hydraulic shocks generated in the system due to the operation of the pump 10 and / or valve assemblies 222, 242.

[0028] In some embodiments, the pump assembly 2, including proportional control valve assemblies 222 and 242 and storage device 170, can be coupled to the hydraulic actuator 3 using, for example, screws, bolts, and / or some other fastening means, thereby reducing the space occupied by the fluid-driven actuator assembly 1. Therefore, as Figure 1 As seen in some exemplary embodiments, the fluid-driven actuator assembly 1 of this disclosure has an integrated configuration that provides a compact design. However, in other embodiments, one or all components of the fluid-driven actuator assembly 1 (such as, for example, the hydraulic pump 10, the hydraulic actuator 3, and / or the control valve assemblies 222 and / or 242) can be individually housed and operatively connected without the need for an integrated configuration. For example, only the pump 10 and the control valves 222, 242 can be combined (or any other combination of devices can be combined).

[0029] Figure 2 An exploded view of an exemplary embodiment of a pump assembly 2 for use with hydraulic actuators (e.g., linear actuators and / or hydrostatic transmission systems) is shown. Pump assembly 2 includes a pump 10 and a storage device 170. Proportional control valve assemblies 222 and 242 are not shown for clarity. The configuration and operation of pump 10 and storage device 170 can be found in the applicant's U.S. Patent Nos. 9,228,586 and 10,294,936, the entire contents of which are incorporated herein by reference. Therefore, for brevity, detailed descriptions of the configuration and operation of pump 10 and storage device 170 are omitted except as necessary to describe this exemplary embodiment. Storage device 170 may be, for example, a pressurized container (e.g., an accumulator) and may be connected to ports 22 and / or 24 via components such as pipes, hoses, channels, or other types of connections (not shown in the figures). Pump 10 includes two fluid actuators 40 and 60, which respectively include a prime mover and a fluid displacement component. Figure 2 In the illustrated exemplary embodiment, the prime mover is an electric motor 41, 61 and the fluid displacement component is a spur gear 50, 70. In this embodiment, the two pump motors 41, 61 are assembled inside the cylindrical openings 51, 71 of the gears 50, 70. However, exemplary embodiments of this disclosure cover other motor / gear configurations. For example, Figure 3 A cross-sectional view of an embodiment of the pump assembly is shown, wherein the motors 41', 61' of the fluid actuators 40' and 60' are mounted on the exterior of the pump interior. Other exemplary pump configurations can be found in U.S. Patent Nos. 9,228,586 and 10,294,936.

[0030] like Figure 2As seen, pump 10 represents a positive displacement (or fixed displacement) gear pump. Gear pairs 50, 70 are housed within an internal volume 98. Each of the gears 50, 70 has a plurality of gear teeth 52, 72 extending radially outward from its respective gear body. The gear teeth 52, 72 transfer fluid from an inlet to an outlet when rotated, for example, by an electric motor 41, 61. Pump 10 may be a variable speed and / or variable torque pump (e.g., motor 41, 61 may be variable speed and / or variable torque), thus the rotation of gears 50, 70 can be varied to produce various volumetric flow rates and pump pressures. In some embodiments, pump 10 is bidirectional (e.g., motor 41, 61 may be bidirectional). In this embodiment, either port 22, 24 may be an inlet port and the other port will be an outlet port, depending on the direction of rotation of gears 50, 70.

[0031] Fluid actuators 40 and 60 are housed within an internal volume 98 defined by the inner wall 26 of the pump housing 20. Shafts 42 and 62 of the fluid actuators 40 and 60 are positioned between ports 22 and 24 of the pump housing 20 and are supported at one end 84 by a plate 80 and at the other end 86 by a plate 82. Stators 44 and 64 of motors 41 and 61 are radially positioned between their respective shafts 42 and 62 and rotors 46 and 66. Stators 44 and 64 are fixedly connected to their respective shafts 42 and 62, which are fixedly connected to the plates 82 and 84 of the housing 20. Rotors 46 and 66 are preferably connected to the fixed shafts 44 and 64 via bearings (not shown). Rotors 46 and 66 are radially outward from and surround the stators 44 and 64. In some embodiments, motors 41 and 61 include housings (not shown) and are coupled to gears 50 and 70 via the motor housings. Therefore, in this embodiment, motors 41 and 61 have an external rotor motor arrangement (or an outer rotor motor arrangement), meaning that the outer side of the motor rotates while the center of the motor is fixed. In contrast, in... Figure 3 In the embodiments, motors 41' and 61' may have an internal rotor motor arrangement in which the rotor is attached to the rotation center shaft.

[0032] like Figure 2As shown, in some embodiments, the storage device 170 may be mounted to, for example, end plate 80 of the pump 10 to form an integrated unit. In some embodiments, the storage device 170 may be disposed separately from the pump 10. The storage device 170 may store fluid drawn by the pump 10 and supply fluid required for executing command operations. In some embodiments, the storage device 170 in the pump 10 may be a pressurized container for storing fluid in the system. In this embodiment, the storage device 170 may be pressurized to a specified pressure suitable for the system. During operation, if the pressure at the relevant ports 22, 24 drops below the pressure in the fluid chamber (not shown) of the storage device 170, pressurized fluid from the storage device 170 may be pushed to the appropriate ports 22, 24 until the pressure equalizes. Conversely, if the pressure at the relevant ports 22, 24 becomes higher than the pressure in the fluid chamber, fluid from the ports may be pushed to the fluid chamber of the storage device 170 via pipes, hoses, channels, or other types of connections (not shown). Those skilled in the art understand the configuration and operation of storage devices in hydraulic systems; therefore, for the sake of brevity, further discussion will not be provided. Although the exemplary embodiments discussed above illustrate only one storage device, exemplary embodiments of this disclosure may have one or more storage devices.

[0033] Figure 4 A top cross-sectional view illustrating the external gear pump 10 and the exemplary fluid flow paths of the pump 10 based on the rotation of gears 50 and 70 (see rotation arrows 74 and 76, respectively) are shown (see flow arrows 92, 94, 94', 96). Although motors 41 and 61 are shown as being housed within the internal volume 98, in some embodiments, one or both motors may be housed outside the internal volume 98. Preferably, the two gears 50 and 70 are independently driven by separately configured motors 41 and 61. Figure 4 In the embodiments described, the gear ratio is 1:1, and for clarity and simplicity, the exemplary embodiments of this disclosure have a 1:1 gear ratio. However, this disclosure is applicable to the control of pumps with gear ratios other than 1:1, and those skilled in the art will understand how to apply the inventive concepts of this disclosure to the control of pumps with various gear ratios.

[0034] Preferably, the pump control circuit 210 is configured to operate the pump in various operating modes, such as controlling processes (e.g., controlling the flow rate and / or pressure in the fluid system 1 to an appropriate operating setpoint or range) and / or controlling the position of the actuator 3 (e.g., positioning the actuator at a predetermined position). It should be noted that the operating modes are not necessarily mutually exclusive. For example, positioning a linear actuator from one end near its stroke to the other end of its stroke may involve the pump control circuit 210 controlling the flow rate and / or pressure of the pumped fluid to an operating setpoint or range, while ultimately setting the actuator position at the predetermined position setpoint.

[0035] like Figure 5 As seen, the pump control circuit 210 may include a pump demand controller 510, a pump operation controller 515, an actuator position controller 520, a motion controller 530, a control mode switch 540, a synchronization position controller 550, a synchronization torque controller 560, a gap feedback circuit 555, a torque feedback circuit 545, and / or motor controllers 570 and 580. The pump operation controller 515 may receive pump operation signals, such as pump start / stop signals and / or pump direction signals, from, for example, a supervisory control unit 266, a drive unit 295, and / or another controller. In some embodiments, the pump operation controller 515 may also receive pump start / stop signals and / or pump direction signals from the actuator position controller 520 (discussed further below). Based on the received signals, the pump operation controller 515 may output an on / off signal 532 to start or stop the pump 10 and / or output a forward / reverse signal 534 to set the rotation direction of the pump 10. Signals 532 and 534 can be sent to motion controller 530, which then outputs individual on / off signals 532A and 532B and forward / reverse signals 534A and 534B to their respective motor controllers 570 and 580 operating motors 41 and 61. In some embodiments, signals 532 and 534 can be sent directly to motor controllers 570 and 580. A power supply (not shown) can supply the required power to motor controllers 570 and 580, enabling them to output the current required to drive their respective motors 41 and 61. Motor controllers 570 and 580 may include hardware such as inverters, IGBT switches, SCRs, and associated controllers to output the required current to motors 41 and 61 based on individual speed demand signals 536A and 536B, respectively. Preferably, motor controllers 570 and 580 are variable speed motor controllers. Variable speed motor controllers are known to those skilled in the art and may be "off-the-shelf" products. Therefore, for the sake of brevity, the configuration of the variable speed motor controller will not be discussed further.

[0036] In some embodiments, the individual speed demand signals 536A, 536B may be based on the required average contact force between gear teeth. For example, the pump operation controller 515 may output a differential speed adjustment signal 516 to the control mode switch 540. Preferably, the differential speed adjustment signal 516 corresponds to the required average contact force between meshing gear pairs. The differential speed adjustment signal 516 may be generated internally by the pump operation controller 515 and / or received from the control unit 266 and / or the drive unit 295 (and / or another controller). Based on the control mode, the differential speed adjustment signal 516 may be output from the control mode switch 540 as a differential demand adjustment signal 542 to the motion controller 530, which uses the differential demand adjustment signal 542 to adjust the individual speed demand signals 536A, 536B.

[0037] In some embodiments, the pump demand controller 510 may provide a pump speed demand signal 536 for controlling, for example, the angular velocity of gears 50, 70 based on, for example, the required flow rate and / or pressure in the system. The pump demand controller 510 may ensure that the flow rate and / or pressure are maintained at their respective flow rate and / or pressure setpoints during various operating modes of the pump control system. An exemplary embodiment of the pump demand controller 510 can be found in U.S. Patent Application No. 15 / 756,928 entitled “System to Pump Fluid and Control Thereof,” the entire contents of which are incorporated herein by reference. However, the type of control scheme used to generate the pump speed demand signal 536 is not limiting, and the exemplary embodiments of this disclosure are applicable to other types of control schemes for generating a pump speed demand signal for controlling the flow rate and / or pressure in a fluid system (e.g., at the output of pump 10). Preferably, the pump speed demand signal 536 may be output to a motion controller 530. Based on the pump demand signal 536 and the differential demand adjustment signal 542, the motion controller 530 generates and outputs individual pump speed demand signals 536A and 536B to the motor controllers 570 and 580, respectively.

[0038] In some embodiments, depending on the operating mode of the pump control system, the actuator position controller 520 can precisely control the positions of motors 41 and 61 to set the position of the fluid-driven actuator 3. Preferably, the actuator position controller 520 can set the position of the fluid-driven actuator 3 based on a reference point (e.g., a fixed reference point). Figure 5As seen, the actuator position controller 520 receives an actuator position setpoint signal 233 (e.g., from control unit 266, drive unit 295, and / or another controller) and one or both position feedback signals 232A, 232B from respective position sensors 231A, 231B. Preferably, when one or both of the feedback signals 232A and 232B deviate from the actuator position setpoint signal 233, the actuator position controller 520 may output start / stop and direction signals to start motors 41, 61 (e.g., via on / off signals 532, 532A, and / or 532B) and, if applicable, provide rotation direction signals (e.g., via forward / reverse signals 534, 534A, and / or 534B). When one or both of the feedback signals 232A and 232B match the actuator position setpoint signal 233, the actuator position controller 520 can stop the motors 41 and 61 (e.g., via on / off signals 532, 532A and / or 532B). Therefore, based on the difference between the position setpoint signal 233 and one or both of the feedback signals 232A and 232B, the actuator position controller 520 can appropriately output start / stop and direction signals to the pump operation controller 515 (and / or directly to the motion controller 530 and / or directly to the motor controllers 570 and 580) to set the position of the actuator 3.

[0039] In some embodiments, the actuator position setpoint signal 233 may be configured to correspond to the desired position of gear 50 and / or gear 70 relative to a fixed reference point (e.g., a point on the pump housing, a point on the motor shaft, or some other point on a non-rotating pump). For example, each motor 41, 61 (and therefore the attached gears) may be set to an angular position corresponding to a 360-degree position on the motor shafts 42, 62 (see [reference]). Figure 4Therefore, in some embodiments, position feedback signals 232A and 232B may be associated with the position of one or more gear teeth 52, 72 relative to a 360-degree position (and / or another fixed position) on shafts 42, 62. In some embodiments, the 360-degree rotational position of each gear 50, 70 may be controlled within 3.6 arcseconds by its respective motor controller 570, 580. Preferably, when controlling the angular velocity of gears 50, 70, the respective motor controller 570, 580 may control the angular velocity within an accuracy of ±0.001 rpm. In operation, if the fluid-driven actuator 3 is required to move the load 300 a fixed distance (e.g., the linear distance of a hydraulic cylinder and the angular movement of a hydraulic motor), the control unit 266 and / or drive unit 295 (and / or another controller) may be configured to determine the precise number of rotations and / or fraction of rotations required by motors 41, 61 (and thus gears 50, 70) to achieve the desired movement of the fluid-driven actuator 3. For example, control unit 266 and / or drive unit 295 (and / or another controller) may determine that, to achieve the desired movement of the hydraulic cylinder or hydraulic motor, the pump will need to rotate +90°, where, for example, "+" indicates pump outflow from port 24 and "-" indicates pump outflow from port 22. In this case, control unit 266 and / or drive unit 295 (and / or another controller) add 90° to the actuator position setpoint signal 233 reaching actuator position controller 520. Actuator position controller 520 compares the actuator position setpoint 233 with the difference between position feedback signals 232A and / or 232B to determine whether the pump should rotate and, if so, in which direction. If repositioning of the fluid-driven actuator 3 is required, the actuator position controller 520 outputs a start signal to turn on the pump 10 (e.g., using on / off signals 532, 532A, and / or 532B via the pump operation controller 515 and / or motion controller 530) and outputs an appropriate rotation direction signal for the pump 10 (e.g., using forward / reverse signals 534, 534A, and / or 534B via the pump operation controller 515 and / or motion controller 530). When position feedback signals 232A and / or 232B from the fluid drives 40 and 60 indicate that the motor / gear has rotated 90°, the actuator position controller 520 sends a stop signal to turn off the pump 10 (e.g., using on / off signals 532, 532A, and / or 532B via the pump operation controller 515 and / or motion controller 530). Although Figure 5The diagram shows an actuator position controller 520, but in some embodiments, two actuator position controllers communicating with each other (e.g., one controller corresponding to each motor) may be used, for example, configured in a master / slave arrangement. Of course, other control schemes can be used by the actuator position controller 520 to set the position of the fluid-driven actuator 3. Preferably, during the stroke time of the fluid-driven actuator 3 (e.g., the time during which motor controllers 570, 580 operate their respective motors 41, 61), the angular velocities of motors 41, 61 and therefore gears 50, 70 are controlled using speed demand signals 536A and 536B (as discussed above, which can be based on speed demand signal 536 and differential demand adjustment signal 542), respectively.

[0040] In some embodiments, the position setpoint signal 233 and / or position feedback signals 232A, 232B correspond to angles within 360 degrees and individually track the number of revolutions required for gears 50, 70 to rotate. However, in other embodiments, the position setpoint signal 233 and / or position feedback signals 232A, 232B may correspond to angles greater than 360 degrees. For example, if pump 10 controls the position of the linear actuator and the motors 41, 61 need to complete 100 revolutions from minimum to full extension on the linear actuator, the motion controller 530 and / or sensors 231A, 231B may be configured such that the minimum position on the linear actuator corresponds to 0 degrees and the maximum position on the linear actuator corresponds to 36000 degrees. Therefore, to move the linear actuator by an amount corresponding to two full rotations on gears 50, 70, the position setpoint signal 233 may be increased by +720 degrees, for example, by control unit 266 and / or drive unit 295 (and / or another controller). Of course, other minimum and maximum degree values ​​may be used.

[0041] In some systems, during pump operation, the pump control system can maintain a fixed speed difference on individual motors to generate the required average contact force, which may correspond to, for example, the force of backflow between sealing gears. Preferably, the pump operation controller 515 can generate a differential speed adjustment signal 516 corresponding to the required contact force, and the differential speed adjustment signal 516 can be sent to a control mode switch 540. Based on the control mode (discussed further below), the control mode switch 540 can select the differential speed adjustment signal 516 and output a differential demand adjustment signal 542 based on the differential speed adjustment signal 516.

[0042] like Figure 5As seen herein, motion controller 530 can receive a pump speed demand signal 536 from pump demand controller 510 and a differential demand adjustment signal 542 from control mode switch 540. Together with the on / off and forward / reverse signals discussed above, and based on the pump speed demand signal 536 and differential demand adjustment signal 542, motion controller 530 can output individual motor speed demand signals 536A and 536B to motor controllers 570 and 580. Speed ​​demand signals 536A and 536B set the appropriate angular velocity of their respective motors 41 and 61 based on the required flow rate and / or pressure, or more specifically, speed demand signals 536A and 536B set the gear speed of the driven gears based on the required flow rate and / or pressure. As used herein, "gear speed" refers to the tip speed of a gear tooth. Therefore, the gear speeds of the gears can be the same, while the angular velocities can be different. For example, if the pump has a 2:1 gear ratio, the speed demand signal to the motor driving the smaller gear can be approximately twice the speed demand signal to the larger gear to adjust the required contact force. Of course, instead of considering the gear ratio of pump 10 in relation to speed demand signals 536A and 536B, motor controllers 570 and 580 can be configured to consider the gear ratio by appropriately modifying the signals to motors 41 and 61. For clarity, speed demand signals 536A and 536B used herein correspond to gear speeds. Therefore, if speed demand signals 536A and 536B are equal, the tip speeds of teeth 52 and 72 are equal (even if the gear angular velocities are different due to a gear ratio other than 1:1).

[0043] Motion controller 530 can generate speed demand signals for motors 41 and / or 61 based on speed demand signal 536, and then modify one or both of the motor speed demand signals for motors 41 and 61 based on differential demand adjustment signal 542 before outputting the signals as speed demand signals 536A, 536B. Therefore, in some embodiments, differential demand adjustment signal 542 is used to generate a difference (also referred to herein as "differential speed demand") to the speed demand signals of motors 41 and 61. Preferably, when control mode switch 540 selects differential speed adjustment signal 516, the differential speed demand corresponds to the desired average contact force. Based on the differential speed demand, speed demand signals 536A and 536B to motor controllers 570 and 580 can be set by motion controller 530 such that one gear rotates slightly faster than the other. However, because the gear teeth are in a meshing configuration, the gears will rotate at the same speed, and the difference in speed demand generates a contact force between opposing gear teeth 52, 72 (assuming a 1:1 gear ratio). In some control systems, the differential speed demand is fixed and preferably related to a predetermined contact force between meshing gear pairs. For example, a differential speed adjustment signal 516 from the pump operation controller 515 may correspond to a predetermined average contact force. The differential speed adjustment signal 516 is used by the motion controller 530 (via the differential demand adjustment signal 542) to adjust one or both of the speed demand signals 536A and 536B, thereby generating a fixed differential speed demand corresponding to the predetermined average contact force. In some embodiments, the fixed speed differential adjustment may be a value based on the type of pump, gear, and / or motor. Preferably, the fixed differential speed demand generates an average contact force sufficient to seal backflow or leakage in the fluid path from the outlet port to the inlet port of the pump 10 and to keep the corresponding torque within an acceptable torque range for the pump motor and / or pump gear. For example, depending on the pump configuration, the predetermined differential speed demand may correspond to a torque value in the range of about 1.0 Nm to about 10 Nm, and more preferably about 1.0 Nm to about 6 Nm. Of course, acceptable torque values ​​and / or ranges can vary depending on, for example, pump size and / or ratings, gear size and / or configuration, motor size and / or configuration, and / or certain other pump / gear / motor parameters. Therefore, when in use, a fixed differential speed requirement can be maintained during pump 10 operation as the pump demand signal 536 causes the motor speed to ramp up and ramp down. However, a fixed differential speed requirement typically does not provide uniform contact force and / or torque between meshing gear pairs. This is because manufacturing tolerances in the gear teeth result in gear teeth with non-uniform dimensions. Variations in gear tooth dimensions can cause contact forces to produce torques less than 1 Nm and / or greater than 10 Nm during gear rotation. Torques less than 1 Nm can lead to inefficient operation due to high backflow or leakage, while torques greater than 10 Nm can cause high stress and / or wear on the teeth. Therefore, in such a system, the torque on individual gear teeth may be too large or too small during pump operation.Aside from the issue of uneven gear tooth dimensions, the fixed differential speed requirement does not take into account changes and / or fluctuations in fluid pressure, pump mechanical vibration, motor electro- / magnetic variations, and / or other disturbances during equipment operation that could affect the torque of the meshing gear teeth. Furthermore, during some operating modes, it may be desirable to operate the pump "inefficiently" to quickly warm the working fluid. For example, the pump may operate using the clearance between corresponding meshing gear pairs to heat the working fluid. Therefore, in this case, a fixed differential speed requirement may not be desirable.

[0044] In some exemplary embodiments of this disclosure, during operation of pump 10, the differential speed demand of speed demand signals 536A, 536B is not fixed, but can be dynamically controlled during operation of pump 10 based on the desired differential torque and / or desired clearance width between one or more pairs of meshing gear teeth 52, 72 of gear pump 10. For example, in some embodiments, pump control circuit 210 may be configured to operate in a synchronized torque operation mode to dynamically synchronize the torque between one or more pairs of meshing gear teeth to generate and / or maintain a predetermined differential torque between the meshing gear teeth. Additionally, in some embodiments, pump control circuit 210 may be configured to operate in a synchronized position operation mode to dynamically synchronize the position between one or more pairs of meshing gear teeth to generate and / or maintain a predetermined clearance width between the meshing gear teeth. In some embodiments, pump control unit 210 includes a control mode switch 540 that sets pump control unit 210 to a synchronized torque operation mode, a synchronized position operation mode, or a fixed speed difference operation mode (as discussed above) based on the value of a received control mode signal 544. Preferably, the value of the control mode signal 544 can be controlled by the supervisory control 266 and / or the drive unit 295 (and / or another controller).

[0045] When the pump control unit 210 is in synchronized torque operation mode, the output of the synchronized torque controller 560 determines the differential speed requirement. For example, the control mode signal 544 may be set such that the control mode switch 540 selects the differential torque adjustment signal 564 from the synchronized torque controller 560. Preferably, the synchronized torque controller 560 is configured such that the differential torque adjustment signal 564 (and therefore the differential requirement adjustment signal 542) can be dynamically changed to maintain the differential torque between the meshing gear pairs 52, 72 at an acceptable value and / or within an acceptable range. In some embodiments, the synchronized torque controller 560 receives a differential torque setpoint signal 562 and a differential torque feedback signal 547 from the torque feedback circuit 545. Preferably, the synchronized torque controller 560 compares the differential torque feedback signal 547 with the differential torque setpoint signal 562 and outputs a comparison-based differential torque adjustment signal 564. For example, the synchronized torque controller 560 may include a lookup table (LUT) or other data structure, a proportional circuit, a proportional-integral (PI) circuit, a proportional-integral-derivative (PID) circuit, and / or another controller or circuit that provides an output signal corresponding to the difference between the differential torque setpoint signal 562 and the differential torque feedback signal 547. Preferably, the value of the differential torque setpoint signal 562 may correspond to an acceptable torque differential value of the meshing gear teeth and / or within an acceptable torque differential range. The differential torque setpoint signal 562 may be set by the supervisory control 266 and / or the drive unit 295 (and / or another controller). Preferably, the pump control circuit 210 includes a torque feedback circuit 545 that determines the torque differential between the meshing gear pairs. In some embodiments, the torque differential may be calculated based on gear size, motor current (e.g., the difference in motor current), and / or the change in one or both motor currents when the meshing gear pairs 52, 72 are in contact with each other. For example, torque differential can be determined by monitoring motor current 543A from motor 41 and motor current 543B from motor 61 and calculating the differential torque between the two motors. The differential torque feedback signal 547 can be based on the difference in motor currents when meshing gear pairs 52, 72 are in contact with each other and / or the instantaneous and / or average changes in one or both motor currents. In other embodiments, the torque differential feedback signal can be based on direct torque measurements (e.g., mechanical and / or electrical), voltage measurements, power measurements, and / or some other type of measurement that provides an indication of the torque differential between meshing gear pairs 52, 72. In some embodiments, the differential torque feedback signal can be calculated by motion controller 530. For example, motor currents 543A and 543B can be input to motion controller 530, which then calculates the differential torque feedback signal.

[0046] When the control mode signal 544 corresponds to the synchronized torque operation mode, the control mode switch 540 selects the differential torque adjustment signal 564 and outputs the differential demand adjustment signal 542 corresponding to the differential torque adjustment signal 564. For example... Figure 5 As seen, the motion controller 530 receives the differential demand adjustment signal 542 and can adjust one or two speed demand signals 536A and 536B based on the differential demand adjustment signal 542. That is, based on the pump demand signal 536 and the differential demand adjustment signal 542, the motion controller 530 generates a differential speed demand and outputs the individual pump demand signals 536A and 536B to the motor controllers 570 and 580 respectively based on the differential speed demand. During the operation of the pump 10 in the synchronized torque operation mode, the synchronized torque controller 560 adjusts the differential torque adjustment signal 564 so that the differential torque feedback signal 547 is maintained at the differential torque setpoint signal 562. Therefore, in the synchronized torque operation mode, the differential speed demand is not a fixed value, but is adjusted to dynamically synchronize the torque between one or more pairs of meshing gear teeth 52, 72 of the gear pump 10. Preferably, the differential speed demand is adjusted such that as gears 50 and 70 rotate and contact each other, the differential torque is controlled to a predetermined value and / or within a predetermined range (e.g., a value from 1 Nm to 10 Nm and / or a range from 1 Nm to 10 Nm, depending on the pump configuration and / or operating conditions). The differential torque value may correspond to an instantaneous value, an average value, and / or some other calculated value. Preferably, the speed demand signal 536A or 536B corresponding to one of gears 50 and 70 is set higher than the other based on the differential torque adjustment signal 564. In some embodiments, the direction of torque adjustment (e.g., the speed demand of gear 50 is faster than that of gear 70 or the speed demand of gear 70 is faster than that of gear 50) can be changed as needed. For example, the adjustment direction may alternate each time pump 10 is started, after a predetermined number of times pump 10 is started, based on operating hours, or some other criterion, such as wear (uniform wear) on each side of gear teeth 52 and 72. The adjustment direction indicator can be a separate signal and / or embedded in the differential torque adjustment signal 564 in some way. For example, the sign "+" or "-" of the differential torque adjustment signal 564 can correspond to which gear has a faster speed requirement. The synchronization torque controller 560, control mode switch 540, and / or motion controller 530 may include hardware and / or algorithms, instruction sets, and / or program code that can be executed by a processor to dynamically adjust one or both of the speed demand signals 536A and 536B during operation of the pump 10 in the synchronization torque operation mode.

[0047] In some exemplary embodiments, the differential torque setpoint signal 562, used by the synchronized torque controller 560 to control the differential speed demand, may be based on a desired slip factor (or slip coefficient or slip flow coefficient), operating conditions (e.g., pressure, flow rate, temperature), gear parameters (e.g., gear profile, mechanical stress limit of gear teeth, or some other gear parameter), motor parameters (e.g., current, voltage, power, or some other motor parameter), and / or some other operating or physical parameter. In some embodiments, for a 1:1 gear ratio, the differential speed demand may be controlled within, for example, the range of 0.0001 degrees / second to 0.001 degrees / second. In some embodiments, depending on the configuration of the pump 10, the differential speed demand may be controlled to produce a differential torque in the range of 1 Nm to 10 Nm, more preferably in the range of 1 Nm to 6 Nm, and even more preferably in the range of 2 Nm to 4 Nm. In some embodiments, depending on the configuration of the pump 10, the differential speed demand may be controlled to provide an average differential torque of approximately 3 Nm ± 0.1 Nm. In some embodiments, the differential torque feedback signal 547 may be based on monitoring the torque difference between one or more representative pairs of meshing gear teeth. Preferably, the differential torque between the representative pairs may be controlled based on a differential torque setpoint signal 562, which is set such that the variance of the differential torque of the remaining meshing gear pairs (e.g., the torque variance attributable to manufacturing tolerances and / or process variances) falls within an acceptable differential torque range. For example, the differential torque setpoint signal 562 may be set (e.g., 3 Nm) such that controlling the differential torque of the representative pairs would mean that the differential torque of the remaining meshing gear teeth would fall within an acceptable range (e.g., between 1 Nm and 6 Nm). In some embodiments, the differential torque between all meshing gear pairs may be monitored. In some embodiments, the monitored torque value for controlling the differential speed requirement may be an instantaneous and / or average differential torque value.

[0048] In some embodiments, the synchronization torque controller 560 may dynamically adjust the differential speed requirement based on an average torque feedback signal derived from data of one or more rotations of gears 50, 70 corresponding to all meshing pairs and / or representative pairs. For example, in some embodiments, the synchronization torque controller 560 may be configured to output a differential torque adjustment signal 564 based on a differential torque feedback signal 547 representing the average differential torque over one or more rotations of all meshing pairs and / or representative pairs. However, while dynamically adjusting the differential speed requirement based on the average differential torque offers advantages over a fixed differential speed requirement, the differential torque values ​​of at least some individual meshing gear pairs may still fall outside acceptable limits (e.g., due to variations in gear tooth dimensions and / or manufacturing processes and / or due to some other reason). That is, even if the average differential torque of the meshing pair (or (several) representative pairs) falls within acceptable limits, the differential torque between some individual meshing gear pairs may still fall outside acceptable limits (e.g., less than 1 Nm and / or greater than 10 Nm).

[0049] Because such variations in differential torque values ​​can exist, in some embodiments, the differential torque between each pair of meshing gear teeth 52, 72 can be monitored, and one or both of the speed demand signals 536A, 536B can be dynamically adjusted tooth by tooth during operation of the pump 10. For example, in some embodiments, the motion controller 530 (and / or another controller) can be configured to keep the differential torque of all meshing pairs within acceptable limits tooth by tooth. Preferably, the differential torque adjustment signal 564 is used by the motion controller 530 (e.g., via the differential demand adjustment signal 542) to generate intermediate or basic differential speed demands for the speed demand signals 536A and 536B. Similar to the differential speed demands discussed above, the basic differential speed demand can be based on the pump demand signal 536 and the differential torque adjustment signal 564 (e.g., via the differential demand adjustment signal 542) and can correspond to the average differential torque of the meshing teeth. However, after the basic differential speed requirements are used to generate the basic speed signals of motor 41 and motor 61, the basic speed signals of motors 41 and 61 can be further modified based on tooth-by-tooth adjustments to generate individual speed requirement signals 536A and 536B, respectively, which are output to motor controllers 570 and 580. That is, when pump 10 is operating, the basic speed signals of motor 41 and / or motor 61 are modified tooth-by-tooth based on individual tooth data (e.g., predetermined data) to generate speed requirement signals 536A and 536B. In some embodiments, the tooth-by-tooth adjustment of the basic speed signals of motor 41 and / or motor 61 can be based on factory calibration and / or in-service calibration of pump 10. Calibration data can be related to individual tooth dimensions, operating data such as motor current and voltage, and / or processing data such as pressure, flow rate, slip factor, etc. The tooth-by-tooth adjustment of the basic speed signals of motor 41 and / or motor 61 can be stored in a data structure (such as, for example, a LUT or some other structure). Preferably, the tooth-by-tooth adjustment used to generate one or both of the speed demand signals 536A and 536B corrects the deviation of the torque value of each pair of meshing gear teeth when they converge in the meshing region 78.

[0050] Preferably, to adjust the torque variance tooth by tooth, the motion controller 530 (and / or another circuit) is configured to make very small incremental adjustments and / or instantaneous adjustments to the angular velocities of motors 41 and 61 based on tooth-by-tooth adjustment data via speed demand signals 536A and 536B, respectively. To this end, in some embodiments, the motion controller 530 (and / or another controller) may receive high-resolution feedback (e.g., via a high-resolution encoder) of the position and / or angular velocity of motors 41 and 61. For example, sensors 231A and / or 231B may provide high-resolution feedback of position and / or angular velocity to their respective motor controllers 570 and 580. Preferably, the motion controller 530 (and / or another controller) may receive one or both of position feedback signals 232A and 232B (and / or velocity feedback) from motor controllers 570 and 580 and determine the position of each tooth relative to a reference point and / or calculate the angular velocities of motors 41 and 61 based on the position feedback signals 232A and 232B. Preferably, the motion controller 530 (and / or another controller) can adjust the motor angular velocity and thus the gear angular velocity in increments of ±0.001 radians / second via, for example, speed demand signals 536A and / or 536B.

[0051] Preferably, the motion controller 530 (and / or another controller) can correlate the position of each pair of meshing gear teeth with the tooth-by-tooth adjustment of that pair. As each pair of meshing gear teeth enters the engagement region 78 (as determined, for example, by position feedback signals 232A and / or 232B), the motion controller 530 (and / or another controller) can, as needed, use the tooth-by-tooth adjustment data to instantaneously modify one or both of the basic speed signals of motors 41 and 61 to generate the final differential speed demand of speed demand signals 536A and 536B. For example, the basic speed signals of motors 41 and / or 61 can be temporarily increased or decreased during the time the meshing gear pairs are in the engagement region 78. After the meshing gear pairs 52, 72 begin to leave the engagement region 78, the modified basic speed signals of motors 41 and / or 61 are reset to the basic speed signal values, and this process is repeated for the next pair of meshing gear teeth 52, 72. Table 1 shows an example of tooth-by-tooth adjustment of each basic speed signal by motion controller 530 (and / or another controller).

[0052] Table 1

[0053]

[0054] In Table 1, the tooth-by-tooth adjustments to the basic speed signals of motor 41 and / or motor 61 are given in positive or negative integer increments. Integers (e.g., 0, ±1, ±2, ...) may correspond to a change in speed percentage (e.g., each integer value may represent, for example, an incremental change of 0.01% in speed requirement), a change in angular velocity (e.g., each integer value represents, for example, an incremental change of 0.001 radians / second), or some other incremental change in the basic speed signal of the respective motor.

[0055] Figure 6A The exemplary curve 600 shown in Table 1 illustrates the adjustment of the pump 10. Figure 6B Plot the interface of the meshing gears MP1 to MPn along the x-axis of curve 600. For example... Figure 6A As seen, the basic speed signal 610 of motor 41 can be set to a value suitable for the required flow rate and / or pressure corresponding to the pump demand signal 536 and the differential torque adjustment signal 564. Figure 6A In this context, because the adjustment of motor 41 (see Table 1) for all meshing pairs MP1 to MPn is 0, the basic speed signal 610 will be the speed demand signal 536A of motor 41. For explanation and clarity, the basic speed signal 610 of motor 41 is shown as constant. However, in actual operation, the basic speed signal 610 of motor 41 and therefore the speed demand signal 536A can vary based on the pump demand signal 536 and / or the differential torque adjustment signal 564. Figure 6A As seen, the basic speed signal 620 of motor 61 (see dashed line) is also at a value suitable for the required flow rate and / or pressure corresponding to the pump demand signal 536 and the differential torque adjustment signal 564. Preferably, the differential speed demand 640 between the basic speed signal 610 of motor 41 and the basic speed signal 620 of motor 61 corresponds to the differential torque adjustment signal 564. As each meshing pair MP1 to MPn enters the meshing region 78, a tooth-by-tooth adjustment (see Table 1 and the y-axis of graph 600) is added to or subtracted from the basic speed signal 620 of motor 61 to produce a speed demand signal 630 corresponding to the speed demand signal 536B. Preferably, the tooth-by-tooth adjustments shown in Table 1 and graph 600 may correspond to a percentage change, an angular velocity change, or some other rotational or positional change. Although the adjustments shown in Table 1 and graph 600 are presented as integer adjustments, the adjustments may be in any format. In some embodiments, the LUT may include actual speed signal values ​​for speed demand signals (e.g., speed demand signals 536A, 536B) rather than adjustments to the basic speed signal. Therefore, in some preferred embodiments, the motion controller 530 (and / or another controller) may be configured to adjust the variation in differential torque between each pair of meshing gear teeth 52, 72 on a tooth-by-tooth basis.

[0056] In some embodiments, to minimize tooth-by-tooth adjustment, the differential torque setpoint signal 562 may be set such that the average differential torque value is in the middle of the acceptable differential torque range (e.g., a setpoint corresponding to 3 Nm of torque within the acceptable torque range of 1 Nm to 5 Nm). Tooth-by-tooth adjustment is preferably performed when the differential torque value falls outside the acceptable torque range and / or to a certain extent keeps the differential torque value within the acceptable torque range. In the above embodiments, the basic speed signal of motor 41 is not modified based on tooth-by-tooth adjustment. However, in other embodiments, the basic speed signal of motor 41 may be modified in place of or together with the basic speed signal of motor 61. By performing tooth-by-tooth adjustment on the basic speed signal, variations in contact force due to, for example, non-uniformity in tooth size (or variations due to some other reason) can be minimized, keeping the contact force within the desired range. Of course, the above control scheme for providing the desired differential speed requirement and / or tooth-by-tooth adjustment is exemplary and other control schemes may be used.

[0057] In some embodiments, the synchronized torque controller 560 may replace the motion controller 530 to provide tooth-by-tooth adjustment. For example, the differential torque adjustment signal 564 output by the synchronized torque controller 560 may contain tooth-by-tooth adjustment information. This tooth-by-tooth adjustment information may then be output in the differential demand adjustment signal 542 by a control mode switch. Preferably, the synchronized torque controller 560 and / or the motion controller 530 (and / or another controller) receive the tooth-by-tooth adjustment information in the differential demand adjustment signal 542 and correlate it with one or both of the position feedback signals 232A and 232B to determine the tooth-by-tooth adjustment of the differential speed demand.

[0058] The synchronized torque controller 560 and / or motion controller 530 (and / or another controller) may include one or more LUTs for providing the aforementioned tooth-by-tooth adjustment. For example, more than one LUT may be used, and different LUTs may be accessed by a suitable controller based on pump size, direction of operation, pump operating speed, pump application (e.g., continuous operation, hydraulic equipment operation, type of fluid being pumped (e.g., abrasive, hydraulic, water, etc.) or some other application), and / or some other criteria. Preferably, the LUTs (several) used for tooth-by-tooth adjustment may be recalibrated (e.g., automatically) based on operating conditions. For example, the LUTs (several) may be recalibrated based on operating hours, number of starts, differential torque (e.g., corresponding to contact force) exceeding a threshold, or for some other reason. In some cases, an alarm may be triggered when the differential torque exceeds a desired range (e.g., corresponding to torque values ​​less than 1 Nm and / or greater than 6 Nm). The alarm may be triggered before any recalibration of the LUT and / or when the adjustment exceeds a threshold (e.g., a threshold when further adjustment is not feasible and / or would destabilize pump control). In some embodiments, a first threshold corresponding to the differential torque may trigger a recalibration, and a second threshold greater than the first threshold may trigger an alarm.

[0059] In some of the exemplary embodiments described above, pump 10 is controlled such that there is contact between meshing gear pairs. However, situations may exist where a gap between corresponding meshing gear pairs is desired. For example, during pump startup, the pumped fluid (e.g., hydraulic fluid in a hydraulic system) may not be at operating temperature. In this case, an inefficiently operating pump (e.g., with excessive backflow or leakage) may heat the fluid faster than a more efficient pump. Similarly, even during normal pump operation, situations may exist where inefficient pump operation is desired, such as when the fluid temperature drops for some reason. A gap may also be desired when pumping abrasive fluids to minimize wear on the teeth.

[0060] In some embodiments, the pump control circuit 210 may include a synchronization position controller 550, which provides a clearance adjustment signal 554 for precisely positioning the motors and / or gears of the pump 10. When the control mode signal 544 is set to position mode, the control mode switch 540 selects the clearance adjustment signal 554 from the synchronization position controller 550 and then outputs a differential demand adjustment signal 542 based on the clearance adjustment signal 554. The motion controller 530 uses the pump speed demand signal 536 and the differential demand adjustment signal 542 to precisely control the position of the motors 41, 61 (e.g., via motor controllers 570 and 580) to control the clearance width between corresponding meshing gear pairs while maintaining the desired flow rate and / or pressure. Preferably, in the synchronization position operation mode, the motion controller 530 instantaneously adjusts the speed demand signals 536A and / or 536B based on the differential demand adjustment signal 542. However, unlike the synchronized torque operating mode, which is designed to generate and / or maintain contact using a predetermined differential torque between corresponding meshing gear pairs, the synchronized position operating mode is designed to generate and / or maintain a predetermined clearance width between corresponding meshing gear pairs. Preferably, the clearance width can range from greater than zero (e.g., the clearance width is close to zero but does not generate contact) to half the clearance between the corresponding gear teeth. In some embodiments, the clearance width can be zero (e.g., just enough to have little or no contact force).

[0061] In some embodiments, the pump control circuit 210 may include a gap feedback circuit 555 for calculating the gap width between corresponding meshing gear pairs. Preferably, the gap feedback circuit 555 receives accurate feedback of the angular positions of motors 41, 61 and / or gears 50, 70 from, for example, position sensors 231A and 231B. For example, in some exemplary embodiments, position sensors 231A and 231B may provide a feedback signal 232A corresponding to the angular position of motor 41 / gear 50 and a feedback signal 232B corresponding to the angular position of motor 61 / gear 70 to the gap feedback circuit 555, respectively. In some embodiments, the gap feedback circuit 555 (and / or another circuit, such as, for example, motor controllers 570 and 580) may determine the position of at least one gear tooth 52 in gear 50 relative to at least one gear tooth 72 in gear 70 based on the position feedback signals 232A, 232B. Preferably, the relative position may be determined to be, for example, within + / - 0.0010° or within + / - 0.0065°. In some embodiments, position sensors 231A and 231B can also measure and / or calculate the angular velocity of the motor / gear shaft.

[0062] Preferably, position sensors 231A and 231B are calibrated based on one or more reference points to measure the angular position of each gear. For example, the position of one or more gear teeth 52 on gear 50 may be related to a 360-degree rotational position on shaft 42 of motor 41, and / or the position of one or more gear teeth 72 may be related to a 360-degree rotational position on shaft 62 of motor 61. One or more reference points can be set as needed. Figure 4 The diagram illustrates illustrative reference points for gear 50, indicating 0 degrees, 90 degrees, 180 degrees, and 270 degrees. Similarly, illustrative reference points for gear 70 are also indicated, indicating 0 degrees, 90 degrees, 180 degrees, and 270 degrees. Figure 4 As seen, the reference designation of gear 70 can be a mirror image of the reference designation of gear 50. Figure 4 In an exemplary embodiment, the 0-degree reference markings of teeth 52, 72 on each gear 50, 70 may correspond to an axis perpendicular to the flow axis of the pump, wherein the 0-degree reference markings face the engagement region 78 of the pump 10. The 180-degree markings of gears 50, 70 may be located on a side away from the engagement region 78. The 90-degree and 270-degree markings of each gear may be parallel to the flow axis, wherein the 90-degree markings of each gear 50, 70 are positioned on the port 24 side and the 270-degree markings of each gear 50, 70 are positioned on the port 22 side. Of course, the configuration of the reference points and degree markings is not limiting, and any desired configuration may be used. For example, one or more reference points may be one or more fixed points mounted on any combination of motors (e.g., shafts), pumps (e.g., housings), or other fixed references. Preferably, the pump 10 includes one or two position sensors 231A, 231B for accurately tracking the rotational position of the respective motor rotors 46, 66 and thus the attached gears 50, 70. Preferably, the position feedback signals 232A and 232B can correlate the position of one or more gear teeth 52, 72 with the 360-degree position on shafts 42, 62.

[0063] In some embodiments, position sensors 231A, 231B may be encoders, such as, for example, optical encoders, magnetic encoders, or another type of encoder capable of measuring the position of rotors 46, 66 and / or gears 50, 70 of motors 41, 61. In some embodiments, position sensors 231A, 231B may measure the angular position of one or more teeth 52, 72 (or other reference points) on gears 50, 70, respectively, within, for example, a range of + / -0.0010° to + / -0.0065°. Figure 4In the case where the shafts are fixed, sensors 231A and 231B can be positioned to measure the angular positions of rotors 46, 66 and / or gears 50, 70 relative to their respective shafts 42, 62 of motors 41, 61. In some embodiments, additional position sensors may be used to monitor rotors 46, 66 and gears 50, 70. In some embodiments, position sensors 231A and 231B can measure the angular positions of rotors 46, 66 and / or gears 50, 70 relative to fixed points on the pump housing. In some embodiments, position sensors 231A and 231B can also measure and / or calculate the angular velocities of the rotors / gears relative to their respective shafts (or fixed points on the pump housing). Preferably, the gap feedback circuit 555 (and / or another circuit, such as motor controllers 570 and 580, for example) includes hardware and / or algorithms, instruction sets and / or program code that can be executed by a processor to correlate the position of at least one protrusion and / or notch (e.g., gear teeth 52, 72) of each gear 50, 70 of the respective fluid drives 40, 60 with a reference point and / or correlate them with each other, based on the position feedback signals 232A, 232B.

[0064] Preferably, the synchronization position controller 550 outputs a gap adjustment signal 554 based on the difference between the gap feedback signal 234 and the gap setpoint 552. In some embodiments, the synchronization position controller may include a LUT or other data structure, a proportional circuit, a PI circuit, a PID circuit, and / or another controller or circuit that outputs a signal correcting the difference between the gap feedback signal 234 and the gap setpoint 552. When in the synchronization position operation mode, the motion controller 530 preferably controls the position of one gear relative to another gear based on a differential demand adjustment signal 542 corresponding to the gap adjustment signal 554. For example, the motion controller 530 may be configured to dynamically synchronize the relative positions between one or more pairs of meshing gear teeth 52, 72 during operation of the gear pump 10 to generate and / or maintain a predetermined gap width. Preferably, based on the differential demand adjustment signal 542, the motion controller 530 adjusts the differential speed demand of speed demand signals 536A and 536B to control the gap width. Preferably, the relative position between corresponding gear teeth can be established based on the distance between a reference point on one tooth and a reference point on another corresponding tooth.

[0065] In an exemplary embodiment, the gap feedback circuit 555 (and / or another circuit) may be configured to generate a gap width G corresponding to one or more pairs of meshing gear teeth 52, 72 (see [reference]). Figure 7 The gap feedback signal 234. For example. Figure 7As seen in some embodiments, the gap feedback circuit 555 may be configured to track at least the center (hereinafter referred to as point C) (or some other reference point) of the crown of one or more teeth on each of the gears 50, 70 and the center of the root of one or more roots on each of the gears 50, 70 (hereinafter referred to as point R) (or some other reference point). Preferably, the gap feedback circuit 555 may track at least one pair of meshing gear teeth 52, 72, having a reference point C on one tooth of the pair and a reference point R on the other tooth of the pair. Of course, the reference point is not limited to the center of the crown and root of the tooth and other locations on the gear may be used as reference points. However, for simplicity and clarity, an exemplary embodiment in which the reference points are points C and R is shown.

[0066] For one or more pairs of meshing gear teeth 52, 72, based on position feedback signals 232A, 232B, the clearance feedback circuit 555 can track reference points C and R on each gear and calculate the distance between the opposing gear tooth surfaces to determine the clearance width G. For example, as gears 50, 70 rotate, the drive position controller 550 can determine the angular position of one or more reference point pairs C and R corresponding to the respective meshing gear teeth pairs relative to a 360-degree angular position on shafts 42, 62 (e.g., discussed above) and / or the relative distance between points C and R. Preferably, the clearance feedback circuit 555 knows the gear dimensions (gear size, gear tooth size, etc.). For example, the gear dimensions can be stored in a data structure (e.g., LUT) or some other data structure accessible to the clearance feedback circuit 555. Based on the angular position and / or relative distance between point pairs C and R when they are closest to each other, the synchronized position controller 550 (and / or motion controller 530 and / or another circuit) can use gear size information to calculate the distance between the opposing gear faces of the gear pair to determine the gap width G between the gear faces.

[0067] Preferably, sensors 231A and 231B can accurately track the positions of one or more reference point pairs C and R corresponding to one or more pairs of meshing gear teeth 52 and 72. For example, in some embodiments, sensors 231A and 231B may include high-resolution encoders with a counting resolution in the range of 100,000 to four million revolutions per revolution, which may depend on the gear design and the motor rpm. Preferably, the drive position controller 550 is configured to receive feedback on the position and / or angular velocity of motors 41 and 61 and therefore gears 50 and 70 via sensors 231A and 231B. Preferably, the resolution of sensors 231A and 231B (e.g., encoders) is high enough that position data is not lost. That is, if the sensor resolution is lower than the operating speed of the pump, the position feedback circuit may miss information from the tracked teeth, such as (e.g.) one or more pulses. Preferably, in embodiments where sensors 231A and 231B are encoders, the encoder count is equal to or greater than 1.5 times the feedback count value corresponding to the fastest pump speed.

[0068] Preferably, when the control mode signal 544 is set to the synchronized position operation mode, the differential demand adjustment signal 542 corresponds to the gap adjustment signal 554. In some embodiments, the synchronized position controller 550 is configured such that the gap adjustment signal 554 changes based on the deviation when the gap feedback signal 234 deviates from the gap setpoint signal 552 (e.g., deviates from a predetermined amount). For example, the synchronized position controller can provide a change in the gap adjustment signal 554, which is used by the motion controller 530 (e.g., via the differential demand adjustment signal 542) to adjust one or both of the speed demand signals 536A and 536B until the gap feedback signal 234 matches the gap setpoint 552 and / or is within a predetermined amount of the gap setpoint 552. The gap feedback signal 234 may be based on the gap width between one or more pairs of representative meshing gear teeth, based on the average gap width between all meshing pairs, and / or based on a tooth-by-tooth calculated gap width.

[0069] During synchronized position operation, motion controller 530 sets speed demand signals 536A and 536B based on pump speed demand signal 536, such that the differential speed demand is zero (e.g., speed demand signals 536A and 536B have the same value). That is, motors 41 and 61 (and therefore gears 50 and 70) rotate at the same tooth speed. When the clearance width G between one or more corresponding meshing gear pairs deviates from the clearance setpoint signal 552 (e.g., deviates from a predetermined amount), synchronized position controller 550 can provide appropriate adjustment of clearance adjustment signal 554, which is received by motion controller 530 via differential demand adjustment signal 542. Motion controller 530 then increases speed demand signal 536A or 536B and / or decreases another speed demand signal 536A, 536B as needed, such that the differential speed demand is non-zero for a predetermined instantaneous period. Preferably, the predetermined instantaneous period is based on gear size. Depending on the gear size, the predetermined instantaneous non-zero time period can be, for example, in the range of 1 to 3 counts on a speed sensor with a high-resolution encoder. In some embodiments, the predetermined instantaneous time period can be in the range of 0.001 seconds to 0.005 seconds. Once the desired gap width G is achieved, the differential speed requirement can be set back to zero by the motion controller 530.

[0070] As discussed above, the clearance feedback signal 234 may be based on the average clearance width G as gears 50, 70 rotate (e.g., representing a representative pair or all pairs). When controlled to the average clearance width G, the instantaneous clearance width G between the meshing gear teeth 52, 72 may be greater than or less than the average due to (e.g.) gear size non-uniformity (or due to some other reason). Therefore, in some embodiments, similar to the synchronized torque mode, the motion controller 530 may control the clearance width G tooth-by-tooth to account for variations in gear size. For example, along with adjusting speed demand signals 536A and / or 536B based on the clearance adjustment signal 554 (via the differential demand adjustment signal 542), the motion controller 530 may include LUTs and / or other data structures that provide further adjustments to the speed demand signals 536A and / or 536B to adjust the clearance width G tooth-by-tooth (e.g., taking into account variations in tooth size). Those skilled in the art will understand that the tooth-by-tooth adjustment of the gap width G and the LUT (and / or other data structure) are similar to the tooth-by-tooth adjustment of the differential torque and the LUT (and / or other data structure). Therefore, for the sake of brevity, a detailed description of the tooth-by-tooth adjustment is omitted. In some embodiments, the synchronized position controller 550 may provide the tooth-by-tooth adjustment via the gap adjustment signal 554.

[0071] In related technical systems, clearance between gears is generally undesirable because it causes more backflow or fluid slip, meaning a relatively high slip factor or slip flow coefficient (a measure of fluid slip) and thus pump inefficiency. However, in exemplary embodiments of this disclosure, the pump can operate in a synchronized position operating mode, where the clearance width G (and therefore the slip flow coefficient or slip factor) can vary based on parameters such as fluid density, viscosity, temperature, pressure, volumetric flow rate, and / or other fluid properties. For example, in a closed-loop system, the working fluid (e.g., hydraulic oil or hydraulic fluid, water, or some other working fluid) may be below its optimal operating temperature and / or viscosity. By operating the pump at a high slip factor (e.g., 6% or greater), the working fluid can be heated, which can reduce its viscosity. While inefficient operation of the pump at a high slip factor is generally undesirable, in some cases, operation at a high slip factor may be more desirable to allow the fluid system to rise to its operating temperature as quickly as possible, for example, in situations where the viscosity of the working fluid is relatively high (e.g., during suction operation startup or if the pump is operating in a cold environment). In this situation, operating the pump using the clearance between meshing gear teeth will result in an increase in the temperature of the working fluid due to the pump's inefficient operation.

[0072] Preferably, the clearance width G can vary from slightly greater than zero to a maximum value of half the gap between the teeth (where the crown of one tooth is centered at the root of the other tooth). In an exemplary embodiment, the clearance width G can be zero, where the gears are in close contact with each other with little or no contact force. Preferably, the motion controller 530 (or another controller) can vary the clearance width G between the meshing gear pairs 52, 72 based on, for example, the temperature of the working fluid, the pump and / or system startup sequence, the operating mode (start, normal, off), and / or some other criterion. For example, the clearance width G can be at its maximum value (where the crown of one gear tooth is precisely centered at the root of the opposing gear) at startup and slowly close until contact is achieved and the startup sequence ends. In another embodiment, the clearance width G can begin to open when the temperature of the working fluid drops below a predetermined temperature and close again as the fluid temperature begins to rise. Preferably, the motion controller 530 (and / or another controller) is configured to receive feedback on the temperature of the working fluid (not shown in the figure). During normal operation, if the temperature of the working fluid drops below a predetermined value, the motion controller 530 (or another controller) can open the gap width G based on the temperature to increase the slip coefficient and heat the working fluid. Therefore, exemplary embodiments of this disclosure allow for a variable slip coefficient during pump operation.

[0073] It should be noted that the clearance width G is limited in the return path. Clearly, if one side of a gear tooth contacts the opposing gear, the other side of the gear tooth will have a clearance corresponding to the full clearance between the teeth. However, the clearance seen in the return path is zero (or close to zero), meaning the return path is obstructed (or nearly obstructed) due to a set of tooth surface contacts. Preferably, when sensors 231A and 231B are encoders, the motion controller 530 can incrementally control the clearance width G based on encoder counts. Preferably, each incremental change ("offset") represents an integer encoder count corresponding to the clearance between the meshing teeth. For example, if each encoder count represents an offset and there are 20 encoder counts corresponding to the clearance between the teeth of a meshing gear pair, the controller can control between an offset of 0 (which may correspond to the point where the gears are in contact) and an offset of 10 (which represents the point where the center of the crown of one gear (e.g., point C) aligns with the center of the root of the other gear (e.g., point R)) (maximum clearance width G). Of course, an offset of 0 can represent the maximum clearance G, and 10 can represent the point of gear contact. If each offset represents the count of two encoders, then in the above scenario, the maximum offset would be 5.

[0074] In some embodiments, the clearance width G can be controlled such that the clearance width G is zero but there is almost no or no contact force (also referred to herein as the "minimum clearance mode"). In the minimum clearance mode, the position of one gear is controlled such that its teeth are just in contact with the teeth of the opposing gear. However, almost no or no force is applied to maintain contact. Therefore, because there is no contact force, the positions of teeth 52, 72 are tracked to ensure contact is present, rather than using other feedback such as motor current. Of course, other feedback such as motor current can still be used to ensure that one gear does not exert too much force on the other gear.

[0075] In minimum clearance mode, the synchronized position controller 550 preferably uses a clearance width setpoint signal 552 at zero. Contact between the teeth is established by tracking the tooth positions (e.g., points C and R) and determining when the gears engage based on the tracked positions and the known dimensions of the gears. Alternatively, or in addition to tracking positions, other feedback discussed above relative to the contact operation mode can be used. In some exemplary embodiments, the predetermined value may be less than 1 Nm or some other value based on system operation and / or architecture. Preferably, if the differential torque reaches or exceeds a predetermined value (e.g., 1 Nm or greater or some other desired value), one or both motors are controlled to reduce the differential torque to zero or near zero, for example, by driving the slower driven gear slightly faster and / or by driving the faster driven gear slightly slower. Preferably, if the differential torque exceeds a predetermined threshold (e.g., 6 Nm or some other desired value), an alarm is triggered to indicate a potential control problem.

[0076] Because there is contact between the opposing gear teeth in minimum clearance mode, backflow or slip flow is minimized, and the slip coefficient is lower than when the clearance width G is greater than zero. Minimum clearance mode represents a highly efficient operating mode for the pump because backflow or slip flow is minimized and almost no additional energy from one or both motors is used to maintain the contact force. Minimum clearance mode is desirable in applications where minimal gear wear is expected and some inefficiency of the pump is acceptable (explained below). For example, if pump 10 pumps abrasive fluids, it is desirable to minimize the contact force on the teeth by operating the system in minimum clearance mode.

[0077] However, minimum clearance mode can sometimes lead to inefficient pump operation because clearance can occasionally form between meshing gear pairs at high gear speeds. Although modern digital control systems have fast update times (clock speeds), the accuracy of gear position and / or gear angular velocity feedback values ​​decreases depending on the pump speed and encoder resolution (e.g., encoder pulses per revolution (PPR) count). Therefore, if the encoder resolution is insufficient, the clearance feedback circuit 555, the synchronized position controller 550, and / or the motion controller 530 (and / or another controller) may not be able to accurately track and control the gear teeth position at higher gear angular velocities and may not be able to maintain gear contact at least until the next update feedback signal. Thus, at high pump speeds relative to the encoder resolution, the motion controller 530 may be unable to maintain gear contact due to limitations of digital control (e.g., the encoder skipping pulses), and this condition persists until the gear teeth position is correctly tracked again. As indicated above, without maintained contact, the slip factor increases and the pump operates inefficiently. Furthermore, the fluid temperature will rise, which reduces viscosity and further degrades pump efficiency. Therefore, although the minimum clearance operation mode provides a balance between tooth wear and pump efficiency when operating the pump within the encoder resolution, when operating at high pump speeds at the edge of the encoder resolution, the pump 10 can be operated in a synchronized torque operation mode (as discussed above) using a torque setpoint 562 of 1 Nm or greater, or based on some other desired value for system operation and / or architecture.

[0078] All or part of the actuator control system 200, including control unit 266 and / or drive unit 295, pump control circuit 210, valve control circuit 220 and / or any other components of the controller, may be implemented in, for example, hardware and / or processor-executable algorithms and / or programming code. The actuator control system 200 including pump control circuit 210 is not limited to, for example... Figure 1Applications such as the hydraulic systems shown are examples. Other applications may include field aviation, automotive, industrial systems, medical systems, agriculture, or any other application requiring pumps. The control unit 266 of the actuator control system 200 may be appropriately configured depending on the type of application, and depending on whether the application requires user input, the control unit 266 may be configured to receive input from the operator's input unit 276. The input unit 276 may be, for example, a control panel, which may include a user interface that allows the operator to communicate with the control unit 266. For example, a control panel may include: digital and / or analog displays, such as (e.g.) LEDs, liquid crystal displays, CRTs, touch screens, meters, and / or any combination of other types of displays, indicators (e.g., on / off LEDs, light bulbs), etc., that transmit information to an operator via a text and / or graphical user interface (GUI); and digital and / or analog input devices, such as touch screens, buttons, dials, knobs, joysticks, and / or other similar input devices; computer terminals or control panels having keyboards, keypads, mice, trackballs, touch screens, or other similar input devices; portable computing devices, such as laptop computers, personal digital assistants (PDAs), mobile phones, digital drawing tablet computers, or some other portable device; or combinations thereof.

[0079] Actuator control system 200 may be provided specifically for controlling fluid-driven actuator system 1 or other applications. Alternatively, control unit 266 may be part of and / or cooperate with another control system in which pump 10 operates, a machine, or another application. Actuator control system 200 (e.g., control unit 266) may include a central processing unit (CPU) that executes various programs such as command operations or pre-programmed routines, algorithms, instructions, and / or other program code. Program data and / or routines may be stored in memory. Routines may also be stored on storage media such as hard disks (HDDs) or portable storage media or may be stored remotely. However, storage media are not limited to the media listed above. For example, routines may be stored on CDs, DVDs, FLASH memory, RAM, ROM, PROM, EPROM, EEPROM, hard disks, or any other information processing device (such as a server or computer) communicating with a computer-aided design station.

[0080] The CPU can be a Xenon or Core processor from Intel (USA) or an Opteron processor from AMD (USA), or other processor types that will be recognized by those skilled in the art. Alternatively, those skilled in the art will recognize that the CPU can be implemented on an FPGA, ASIC, PLD, or using discrete logic circuitry. Furthermore, the CPU can be implemented as multiple processors working in parallel to execute command operations or pre-programmed routines.

[0081] The actuator control system 200 (e.g., control unit 266) may include a network controller for interfacing with a network, such as an Intel Ethernet PRO network interface card from Intel Corporation. It should be understood that the network may be a public network such as the Internet, a private network such as a LAN or WAN, or any combination thereof, and may also include PSTN or ISDN subnets. The network may also be wired (e.g., Ethernet) or wireless (e.g., cellular networks, including EDGE, 3G, and 4G wireless cellular systems). The wireless network may also be WiFi, Bluetooth, or any other known form of wireless communication. The actuator control system 200 (e.g., control unit 266) may receive commands from the operator via a user input device such as a keyboard and / or mouse, either wired or wirelessly. Furthermore, communication between control unit 266, drive unit 295, motor controllers 570, 580, and valve controller may be analog or via a digital bus and may use known protocols such as Controller Area Network (CAN), Ethernet, Common Industry Protocol (CIP), Modbus, and other well-known protocols.

[0082] Embodiments of the controllers and / or modules in this disclosure may be provided as hard-wired circuitry and / or computer program products. As a computer program product, the product may include machine-readable media on which instructions are stored, which can be used to program a computer (or other electronic device) to perform processing. Machine-readable media may include (but are not limited to) floppy disks, optical disks, optical disc read-only memory (CD-ROM) and magneto-optical disks, ROMs, random access memory (RAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), vehicle identification modules (VIMs), magnetic cards or optical cards, flash memory, or other types of media / machine-readable media suitable for storing electronic instructions.

[0083] The term "module" broadly refers to a software, hardware, or firmware component (or any combination thereof). A module is typically a functional component that can produce useful data or other outputs using specified inputs(s). Modules may or may not be independent. The controller discussed above may contain one or more modules.

[0084] Although the above-described drive-drive embodiments are described relative to an external gear pump configuration including a spur gear with gear teeth, it should be understood that those skilled in the art will readily recognize that the concepts, functions, and features described below are readily applicable to: external gear pumps with other gear configurations (helical gears, herringbone gears, or other gear tooth configurations suitable for driving fluids); internal gear pumps with various gear configurations; pumps with two or more prime movers; prime movers other than electric motors, such as hydraulic motors or other fluid-driven motors, internal combustion engines, gas engines, or other types of engines, or other similar devices that can drive fluid displacement components; and fluid displacement components other than external gears with gear teeth, such as internal gears with gear teeth, hubs (e.g., discs, cylinders, other similar components) with protrusions (e.g., bumps, extensions, protrusions, projections, other similar structures, or combinations thereof), hubs (e.g., discs, cylinders, or other similar components) with notches (e.g., cavities, recesses, gaps, or other similar structures), gear bodies with blades, or other similar structures that can discharge fluid during drive. Therefore, for the sake of brevity, detailed descriptions of various pump configurations are omitted. Furthermore, those skilled in the art will recognize that, depending on the type of pump, contact (drive-drive) can help to draw fluid in place of or together with a sealed reverse flow path. For example, in a certain internal gear rotor pump configuration, contact or engagement between two fluid displacement components can also help to draw fluid trapped between the teeth of opposing gears. Moreover, although the above embodiments include fluid displacement components with an external gear configuration, those skilled in the art will recognize that, depending on the type of fluid displacement component, contact or engagement is not limited to side-to-side contact, but can be located between any surface of at least one protrusion (e.g., bump, extension, projection, protrusion, other similar structure or combination thereof) on one fluid displacement component and any surface of at least one protrusion (e.g., bump, extension, projection, protrusion, other similar structure or combination thereof) or recess (e.g., cavity, recess, void or other similar structure) on another fluid displacement component.

[0085] Fluid displacement components (such as gears in the above embodiments) may be made entirely of either metallic or non-metallic materials. Metallic materials may include (but are not limited to) steel, stainless steel, anodized aluminum, aluminum, titanium, magnesium, brass, and their respective alloys. Non-metallic materials may include (but are not limited to) ceramics, plastics, composites, carbon fibers, and nanocomposite materials. Metallic materials may be used, for example, in pumps requiring robustness to withstand high pressures. However, non-metallic materials may be used for pumps used in low-pressure applications. In some embodiments, the fluid displacement component may be made of an elastic material (e.g., rubber, elastomeric materials) to further reinforce the sealing area, for example.

[0086] Alternatively, fluid displacement components (such as the gears in the above embodiments) can be made from a combination of different materials. For example, the body can be made of aluminum, and the portion that contacts another fluid displacement component (such as the gear teeth in the above exemplary embodiments) can be made of steel (for pumps requiring robustness to withstand high pressure), plastic (for pumps used in low-pressure applications), elastomeric materials, or another suitable material (depending on the type of application).

[0087] Exemplary embodiments of fluid delivery systems can discharge a variety of fluids. For example, a pump can be configured to pump hydraulic fluids, engine oil, crude oil, blood, liquid pharmaceuticals (syrups), paints, inks, resins, adhesives, molten thermoplastics, tar, asphalt, molten molten chocolate, water, acetone, benzene, methanol, or another fluid. As can be seen from the types of fluids that can be pumped, exemplary embodiments of pumps can be used in a variety of applications, such as heavy industrial machinery, aerospace applications, automotive applications, the chemical industry, the food industry, the medical industry, commercial applications, residential applications, or another industry that uses pumps. Factors such as fluid density, viscosity, fluid temperature, the required pressure and flow rate of the application, the configuration of fluid displacement components, the size and power of the motor, physical space considerations, the weight of the pump, or other factors affecting pump configuration will play a role in pump arrangement. Considering the type of application, the exemplary embodiments of fluid delivery systems discussed above can have an operating range falling within, for example, from 1 rpm to 5000 rpm. However, in aerodynamic applications, pumps can have an operating range of 6,000 rpm to 12,000 rpm or greater. Of course, this range is not limiting and other ranges are feasible.

[0088] Furthermore, the dimensions of fluid displacement components can vary depending on the pump application. For example, when gears are used as fluid displacement components, the circular pitch of the gears can range from less than 1 mm (e.g., nylon nanocomposites) to several meters in width for industrial applications. The thickness of the gears will depend on the required pressure and flow rate of the application.

[0089] Although the invention has been disclosed with reference to specific embodiments, numerous modifications, alterations, and variations may be made to the described embodiments without departing from the scope and definition of the invention as defined in the appended claims. Therefore, the invention is not intended to be limited to the described embodiments, but rather has the full scope defined by the language of the following claims and their equivalents.

Claims

1. A device for controlling a gear pump, comprising: The torque adjustment circuit is configured to receive a torque setpoint and a torque feedback signal corresponding to the differential torque between a pair of meshing gear teeth of the first gear and the second gear. The torque adjustment circuit is further configured to output a torque adjustment signal corresponding to the difference between the torque setpoint and the torque feedback signal. and The motion control circuit is configured as follows: The first speed demand signal is provided to the first motor driving the first gear, and the second speed demand signal is provided to the second motor driving the second gear. The torque between the teeth of the pair of meshing gears is dynamically synchronized by adjusting at least one of a first speed demand signal or a second speed demand signal based on a torque adjustment signal, so that the differential torque between the teeth of the pair of meshing gears is within a predetermined range. The torque feedback signal is based on the average differential torque of at least one rotation of the first or second gear between the teeth of each pair of meshing gears, and The torque setpoint is based on the average torque value of the pair of meshing gear teeth.

2. The apparatus of claim 1, wherein the torque feedback signal is based on at least one of a first motor current of a first motor or a second motor current of a second motor.

3. The apparatus of claim 1 or claim 2, wherein the motion control circuit is configured to receive a speed demand signal corresponding to a predetermined speed of the first gear and the second gear, and The adjustment of at least one of the first speed demand signal or the second speed demand signal is further based on the speed demand signal.

4. The apparatus of claim 1 or claim 2, wherein at least one of the adjustment of the first speed demand signal or the second speed demand signal is performed tooth by tooth.

5. The apparatus of claim 4, wherein the tooth-by-tooth adjustment corresponds to a predetermined adjustment stored in a data structure.

6. The apparatus of claim 1 or claim 2, wherein the predetermined range is between 1 Nm and 10 Nm, including 1 Nm and 10 Nm.

7. A pump system, comprising: Pump assembly, including The pump casing defines the internal volume. The first gear and the second gear are housed within the internal volume such that the first gear meshes with the second gear. The first motor is used to drive the first gear, and The second motor is used to drive the second gear; and Controller circuit, including The torque adjustment circuit is configured to receive a torque setpoint and a torque feedback signal corresponding to the differential torque between a pair of meshing gear teeth of the first gear and the second gear. The torque adjustment circuit is further configured to output a torque adjustment signal corresponding to the difference between the torque setpoint and the torque feedback signal. and The motion control circuit is configured as follows: The first speed demand signal is provided to the first motor driving the first gear, and the second speed demand signal is provided to the second motor driving the second gear. The torque between the teeth of the pair of meshing gears is dynamically synchronized by adjusting at least one of a first speed demand signal or a second speed demand signal based on a torque adjustment signal, so that the differential torque between the teeth of the pair of meshing gears is within a predetermined range. The torque feedback signal is based on the average differential torque of at least one rotation of the first or second gear between the teeth of each pair of meshing gears, and The torque setpoint is based on the average torque value of the pair of meshing gear teeth.

8. The system of claim 7, wherein the torque feedback signal is based on at least one of the first motor current of the first motor or the second motor current of the second motor.

9. The system of claim 7 or claim 8, wherein the motion control circuit is configured to receive a pump speed demand signal corresponding to at least one of a predetermined flow rate setpoint or a predetermined pressure setpoint, and The adjustment of at least one of the first speed demand signal or the second speed demand signal is further based on the pump speed demand signal.

10. The system of claim 7 or claim 8, wherein at least one of the adjustment of the first speed demand signal or the second speed demand signal is performed tooth by tooth.

11. The system of claim 10, wherein the tooth-by-tooth adjustment corresponds to a predetermined adjustment stored in a data structure.

12. The system of claim 7 or claim 8, wherein the predetermined range is between 1 Nm and 10 Nm, including 1 Nm and 10 Nm.

13. A method for controlling a pump motor in a drive-drive configuration, the method comprising: The first speed demand signal is provided to the first motor that drives the first gear; The second speed demand signal is provided to the second motor that drives the second gear; Receive torque setpoint; Receive torque feedback signal corresponding to the differential torque between a pair of meshing gear teeth of the first gear and the second gear; Output a torque adjustment signal corresponding to the difference between the torque setpoint and the torque feedback signal; and The torque between the teeth of the pair of meshing gears is dynamically synchronized by adjusting at least one of a first speed demand signal or a second speed demand signal based on a torque adjustment signal, so that the differential torque between the teeth of the pair of meshing gears is within a predetermined range. The torque feedback signal is based on the average differential torque of at least one rotation of the first or second gear between the teeth of each pair of meshing gears, and The torque setpoint is based on the average torque value of the pair of meshing gear teeth.

14. The method of claim 13, wherein the torque feedback signal is based on at least one of a first motor current of a first motor or a second motor current of a second motor.

15. The method of claim 13 or claim 14, further comprising: Receive speed demand signals corresponding to the predetermined speeds of the first and second gears. The adjustment of at least one of the first speed demand signal or the second speed demand signal is further based on the speed demand signal.

16. The method of claim 13 or claim 14, wherein the adjustment of at least one of the first speed demand signal or the second speed demand signal is performed tooth by tooth.

17. The method of claim 15, wherein the predetermined range is between 1 Nm and 10 Nm, including 1 Nm and 10 Nm.

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